1. The problem statement, all variables and given/known data Show that a(x) =( -cos(2x)), -2*cos(x), sin (2x)) is a sphere curve by showing that (-1,0,0) belongs to each normal plane. 2. Relevant equations Not quite sure (part of my question) T= a'(x) N= T'/norm(T') B= T x N (T cross N) 3. The attempt at a solution Ok I found the values of the Tangent field, the Binormal Field, and the Normal field vectors to be certain values and have attempted to demonstrate, by finding a value of x for each of the fields, that the point exists for all three of the planes. However, I don't think this is what should have been done. In fact I am frankly confused as to how exactly to go about showing the asked statement is true. So I guess what I am asking for is did I do this right (see work below), or am I in the wrong frame of mind? T= (2 sin(2x), 2 sin(x), 2 cos(2x)) N=( (4 cos(2x), 2 cos(x), -4sin(2x))/(sqrt(cos^2(x)+4) (B is kind of nasty to write up without latex...so I will work on that one, but for the time being if you need to figure it out just go with B = T cross N). Thanks for any help.